The twelve Hindu months

A lunar month

A Hindu month (masa) is one full cycle of the Moon, from New Moon to the next New Moon, about 29.5 days. Twelve such months make a lunar year of about 354 days, a little shorter than a solar year. To keep the months in line with the seasons, an extra month (adhika masa) is added about every three years.

Each month has two halves, the Shukla paksha and the Krishna paksha, with 15 tithis in each.

The twelve names

The months begin with Chaitra, the month in which spring arrives and the new year starts in the main North Indian count.

Names are spelled in different ways: Ashwin or Ashvina, Kartik or Kartika, Pausha or Pushya, Margashirsha or Agrahayana or Margashira. All refer to the same months.

Why these names

Each month is named after the nakshatra, or star group, in which the Full Moon falls. When the Full Moon is near the star Chitra, the month is Chaitra. When it is near Vishakha, the month is Vaishakha. In the same way Jyeshtha, Ashadha, Shravana, Bhadrapada, Ashwini, Krittika (Kartika), Mrigashira (Margashirsha), Pushya (Pausha), Magha and Phalguni (Phalguna) give their names to the other months.

Two ways to name the Krishna paksha

Not every region draws the line between months in the same place.

• Purnimanta (North India): the month ends on Purnima. The Krishna paksha is counted with the next month.
• Amanta (Gujarat, Maharashtra, South India): the month ends on Amavasya. The Krishna paksha stays with the month it follows.

The Shukla paksha has the same month name in both systems. The Krishna paksha has different names. A Krishna paksha that is called Ashwin in the Amanta calendar is called Kartika in the Purnimanta calendar. The site shows the Purnimanta name first and the Amanta name beside it. The page on Amanta and Purnimanta has the full explanation.

Solar months and the adhika masa

The Sun also moves through twelve signs, and its entry into a new sign is called a sankranti. A lunar month with no sankranti in it is the extra month, adhika masa. Its name repeats the month that follows or precedes it, and festivals are generally not held in it. Occasionally a month can be dropped, but this is very rare. Some regional calendars, such as the Tamil and Malayalam ones, follow the solar months directly.

Using months in a date

A festival date is written as month, paksha and tithi, for example "Phalguna Purnima". For festivals that fall in the Shukla paksha, both systems agree. For a Krishna paksha festival, always check which system the source uses, and remember that Diwali, for example, is Ashwin Amavasya in the Amanta system and Kartika Amavasya in the Purnimanta system, while the day is the same.

Local practice in the USA

Temples in the USA often follow the tradition of their community. A Gujarati temple will usually speak of Amanta months. A North Indian temple will use Purnimanta. A south Indian temple will usually follow its own regional calendar. None is wrong. Choose the one your family follows.